net: nrf_provisioning: Move all processing into own workq

Define a worke queue, instead of thread and run all
longer running processes from this work queue.

Refactor the previous background thread to be a
delayable work item for this queue.

This way we don't accidentally block system work queue
on initialization phase.

Signed-off-by: Seppo Takalo <[email protected]>

Author: SeppoTakalo

include/net/nrf_provisioning.h

@@ -91,6 +91,9 @@ struct nrf_provisioning_dm_change {
  * Feeding a null as a callback address means that the corresponding default callback function is
  * taken into use.
  *
+ * This function return immediately after configuring the callbacks and schedules
+ * longer initialization work to be done in the background.
+ *
  * @param mmode Modem mode change callback. Used when data is written to modem.
  * @param dmode Device mode callback. Used when provisioning state changes.
  * @return <0 on error, 0 on success.

samples/cellular/nrf_provisioning/src/main.c

@@ -133,24 +133,6 @@ static void device_mode_cb(enum nrf_provisioning_event event, void *user_data)
 static struct nrf_provisioning_mm_change mmode = { .cb = modem_mode_cb, .user_data = NULL };
 static struct nrf_provisioning_dm_change dmode = { .cb = device_mode_cb, .user_data = NULL };
 
-/* Work item to initialize the provisioning library and start checking for provisioning commands.
- * Called automatically the first time network connectivity is established.
- * Needs to be a work item since nrf_provisioning_init may attempt to install certs in a blocking
- * fashion.
- */
-static void start_provisioning_work_fn(struct k_work *work)
-{
-	LOG_INF("Initializing the nRF Provisioning library...");
-
-	int ret = nrf_provisioning_init(&mmode, &dmode);
-
-	if (ret) {
-		LOG_ERR("Failed to initialize provisioning client, error: %d", ret);
-	}
-}
-
-static K_WORK_DEFINE(start_provisioning_work, start_provisioning_work_fn);
-
 /* Callback to track network connectivity */
 static struct net_mgmt_event_callback l4_callback;
 static void l4_event_handler(struct net_mgmt_event_callback *cb,
@@ -166,13 +148,15 @@ static void l4_event_handler(struct net_mgmt_event_callback *cb,
 		k_event_clear(&prov_events, NETWORK_DOWN);
 		k_event_post(&prov_events, NETWORK_UP);
 
-		/* Start the provisioning library after network readiness is first established.
-		 * We offload this to a workqueue item to avoid a deadlock.
-		 * (nrf_provisioning_init might attempt to install certs, and in the process,
-		 * trigger a blocking wait for L4_DOWN, which cannot fire until this handler exits.)
-		 */
+		/* Start the provisioning library after network readiness is first established.	 */
 		if (!provisioning_started) {
-			k_work_submit(&start_provisioning_work);
+			LOG_INF("Initializing the nRF Provisioning library...");
+
+			int ret = nrf_provisioning_init(&mmode, &dmode);
+
+			if (ret) {
+				LOG_ERR("Failed to initialize provisioning client, error: %d", ret);
+			}
 			provisioning_started = true;
 		}
 	}

subsys/net/lib/nrf_provisioning/include/nrf_provisioning_internal.h

@@ -16,13 +16,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief Background provisioning service - assumed to run in its own thread.
- *
- * Revealed only to be able to test the functionality.
- */
-int nrf_provisioning_req(void);
-
 /**
  * @brief Seconds to next provisioning
  *